New Tube amp- HUM on stand buy, also strong HUM when using FX loop

johnmontana

Hi there,
Is it normal to have a  HUM on stand buy position? When fully turned on, the amp goes a bit quieter than the hum is coming back in few secs....
Also the FX loop have a strong hum noise even when a patch lead connected (no pedals)
Is this stuff common to tube amps or an easy fix  or I should just return the amp?

I am not good in tech stuff so please don't bombard me with all sorts of abbreviations etc...

Cheers!

Fez

What amp is it?

Sounds like it's new, is it?

johnmontana

It is a ZubZero 50w head, yes, brand new.

ICBM

That doesn't sound right. If it's new, you may want to take it up with the shop, if you're not good with tech stuff yourself.

Are you powering the FX in the loop from the same power supply as the ones in front of the amp? That can cause a bad hum if the supply doesn't have fully isolated outputs.

johnmontana

The pedals were battery powered...also tried with just a patch lead... nothing changed, same loud hum noise

ICBM

johnmontana said:

The pedals were battery powered...also tried with just a patch lead... nothing changed, same loud hum noise

Definitely faulty.